Neuron Smear
Spinal Cord
Cerebellum
Cerebrum
White matter
Grey Matter
Histology Terms
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Nissl bodies: Large granular bodies found in neurons. These granules are of rough endoplasmic reticulum (RER)
with rosettes of free ribosomes, and are the site of protein synthesis.
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Neuropil, sometimes referred to as "neuropile," is a broad term defined as any area in the nervous system
composed of mostly unmyelinated axons, dendrites and glial cell processes that forms a synaptically dense region
containing a relatively low number of cell bodies. The most prevalent anatomical region of neuropil is the brain
which, although not completely composed of neuropil, does have the largest and highest synapticallyconcentrated areas of neuropil in the body. For example, theneocortex and olfactory bulb both contain neuropil
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White matter, named for its relatively light appearance resulting from the lipid content of myelin, refers to axon
tracts and commissures.
White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed
largely of lipid tissue veined with capillaries. Its white color in prepared specimens is due to its usual preservation in
formaldehyde.
White matter, long thought to be passive tissue, actively affects how the brain learns and functions. While grey
matter is primarily associated with processing and cognition, white matter modulates the distribution of action
potentials, acting as a relay and coordinating communication between different brain regions.
Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and
myelinated as well as unmyelinated axons), glial cells (astroglia and oligodendrocytes), synapses, and capillaries.
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The name granule cell has been used by anatomists for a number of different types of neuron whose only
common feature is that they all have very small cell bodies. Granule cells are found within the granular layer of the
cerebellum, the dentate gyrus of the hippocampus, the superficial layer of the dorsal cochlear nucleus,
theolfactory bulb, and the cerebral cortex.
Cerebellar granule cells account for the majority of neurons in the human brain.
At the top of the cerebellum lies the molecular layer, which contains the flattened dendritic trees of Purkinje
cells, along with the huge array of parallel fibers penetrating the Purkinje cell dendritic trees at right angles.
Purkinje cells receive more synaptic inputs than any other type of cell in the brain—estimates of the number of spines on a single
human Purkinje cell run as high as 200,000. The large, spherical cell bodies of Purkinje cells are packed into a narrow layer (one
cell thick) of the cerebellar cortex, called the Purkinje layer.
Histology Terms Continued
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Lamellar corpuscles, or Pacinian corpuscles, are one of the four major types of mechanoreceptor. They
are nerve endings in the skin responsible for sensitivity to vibration and pressure.[1] They respond only to
sudden disturbances and are especially sensitive to vibration.[2] The vibrational role may be used to
detect surface texture, e.g., rough vs. smooth. Lamellar corpuscles are also found in the pancreas, where
they detect vibration and possibly very low frequency sounds.[3] Lamellar corpuscles act as very rapidly
adapting mechanoreceptors. Groups of corpuscles respond to pressure changes, e.g. on grasping or
releasing an object.
Microglia are a type of glial cell located throughout the brain and spinal cord. Microglia account for
10–15% of all cells found within the brain. As the resident macrophage cells, they act as the first
and main form of active immune defense in the central nervous system (CNS).
Glomerulus is a common term used in anatomy to describe globular structures of entwined vessels,
fibers, or neurons. Latin glomus, meaning "ball of yarn".
Cerebellum